I am puzzled about the bolometric correction for stars like this. The planets receive enough IR to have Goldilocks temperatures, but their visual illuminance can only be a few hundred to a couple of thousand lux. Which means that their full sunlight is only as bright as office lighting, and their partial shade correspondingly stygian. We know that the availability of light constraints plant growth on Earth; there is no reason to believe that an efficient photosynthesis is possible with IR and it seems unlikely on photo-chemical grounds. So if there is life on these planets its photosynthesis can only be crawling along at under 1% of the areic rate on Earth. And that means an oxygen catastrophe at ~200 billion years system age rather than ~2 billion years system age. To find free oxygen in their atmospheres seems very unlikely even if they are life-bearing, but no-one ever seems to mention this.

I am puzzled about the bolometric correction for stars like this. The planets receive enough IR to have Goldilocks temperatures, but their visual illuminance can only be a few hundred to a couple of thousand lux. Which means that their full sunlight is only as bright as office lighting, and their partial shade correspondingly stygian. We know that the availability of light constraints plant growth on Earth; there is no reason to believe that an efficient photosynthesis is possible with IR and it seems unlikely on photo-chemical grounds. So if there is life on these planets its photosynthesis can only be crawling along at under 1% of the areic rate on Earth. And that means an oxygen catastrophe at ~200 billion years system age rather than ~2 billion years system age. To find free oxygen in their atmospheres seems very unlikely even if they are life-bearing, but no-one ever seems to mention this.

There may well be more efficient forms of photosynthesis, or other processes serving the same function for plants, which never took off on Earth because photosynthesis was good enough and the ancestors of our extant photosynthetic life outperformed organisms using those hypothetical mechanisms under the light-rich conditions on Earth.

On the other hand, I am more concerned that all over these planets are likely to be tidally locked to their parent star, as close as they are to it. That has got to be a serious obstacle for life.

_________________Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards. Sir Frederick HoyleEarth is the cradle of humanity, but one cannot live in a cradle forever. Konstantin TsiolkovskyMan has earned the right to hold this planet against all comers, by virtue of occasionally producing someone completely bat**** insane. xkcd #556Just like people, stars can be very important without being terribly bright. Phil Plait, "Bad Astronomy"

There may well be more efficient forms of photosynthesis, or other processes serving the same function for plants, which never took off on Earth because photosynthesis was good enough and the ancestors of our extant photosynthetic life outperformed organisms using those hypothetical mechanisms under the light-rich conditions on Earth.

That's logically possible, but not physically plausible. IR photons simply don't contain enough energy to drive photosynthesis without multpile-photon capture and energy storage arrangements. They just aren't energetic enough to do the right sorts of things to molecular bonds. Visible light works well for photosynthesis because each photon of it contains enough energy to reform a bond in an organic molecule (but not so much as to destroy an organic pigment). Besides, there are gradients in Earth's environment from well-lit to dark that would provide a selective pressure to favour any more efficient forms of photosynthesis. Earth is not uniformly light-rich: there are forest understoreys, deep waters, caves, winter days.

Yes, it is a flare star, which doesn't bode well for the 3 planets in the habitable zone.

I LOVE that our current planetary formation theories cannot explain how 7 planets can orbit so close to this star. I suspect there may be a gas giant hiding out in the dark that we haven't found yet helping to keep everything in place. It could also have pushed the worlds inward.

The 7 known worlds all seem to be in orbital resonances, which is also cool.

Who is online

Users browsing this forum: No registered users and 1 guest

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum